Control device and vehicle

Abstract

Provided are a control device and a vehicle that can switch an operation line of an internal combustion engine regardless of an operation point of the internal combustion engine, while reducing a sense of strangeness felt by an occupant. The control device is a control device of a vehicle that includes an internal combustion engine, a generator that can rotate under the action of the internal combustion engine, a storage battery that stores electric power generated by rotation of the generator, and an electric motor that is supplied with electric power from the storage battery and outputs drive power to a drive wheel, starts to increase a rotational speed of the internal combustion engine to a rotational speed set in rich operation in which a ratio of fuel to oxygen of the internal combustion engine is higher than a stoichiometric ratio, at a timing at which an output required when the internal combustion engine is operated at a stoichiometric ratio becomes a threshold value or more in a state in which the internal combustion engine is not mechanically linked to the drive wheel.

Description

Technical Field

[0001] This invention relates to a control device and a vehicle. Background Technology

[0002] Techniques for controlling the speed and torque of an internal combustion engine in a hybrid vehicle are known. For example, Japanese Patent Application Publication No. 2018-127961 discloses a hybrid vehicle that reduces fluctuations in speed and torque when operating conditions change. This technique switches operating conditions between multiple operating lines when the speed and torque of the internal combustion engine meet predetermined conditions. Summary of the Invention

[0003] However, in the technology described in Japanese Patent Application Publication No. 2018-127961, the timing for switching the operating line of the internal combustion engine is limited. Thus, in conventional technology, it is sometimes impossible to achieve the following: switching the operating line of the internal combustion engine regardless of its operating point, while simultaneously reducing discomfort felt by the occupants.

[0004] The present invention was made in consideration of such circumstances, and one of its objectives is to provide a control device and vehicle that can switch the operating line of the internal combustion engine regardless of the operating point of the internal combustion engine, while reducing the discomfort felt by the occupants.

[0005] The control device and vehicle of the present invention adopt the following structure.

[0006] (1): One aspect of the control device of the present invention is a vehicle control device, the vehicle comprising: an internal combustion engine, a generator that can rotate under the action of the internal combustion engine, a battery that stores the electricity generated by the rotation of the generator, and an electric motor that is supplied with electricity from the battery and outputs driving force to the drive wheels, wherein when the internal combustion engine operates in a state where the internal combustion engine is not mechanically connected to the drive wheels, and when the required output for the internal combustion engine to operate at a stoichiometric ratio according to the stoichiometric air-fuel ratio becomes higher than a threshold, the speed of the internal combustion engine is increased to the speed set in rich operation where the ratio of fuel to oxygen in the internal combustion engine is higher than the stoichiometric air-fuel ratio.

[0007] (2): In the above (1) scheme, when the internal combustion engine is in operation and is in the state of not being mechanically connected to the drive wheel, the control device increases the speed of the internal combustion engine to the speed set in the rich operation, and then switches the stoichiometric operation to the rich operation to increase the torque of the internal combustion engine, and limits the rate of increase of the torque.

[0008] (3): In the above scheme (2), the lower the speed of the vehicle, the more the control device restricts the rate of increase of torque.

[0009] (4): In any of the above (1) to (3), when the internal combustion engine is in operation and is in the state where the internal combustion engine and the drive wheel are not mechanically connected, the control device increases the speed of the internal combustion engine to the speed set in the rich operation, and then switches the stoichiometric operation to the rich operation to increase the output of the electric motor, thereby limiting the rate of increase of the output.

[0010] (5): In the above scheme (4), the lower the speed of the vehicle, the more the control device restricts the rate of increase of the output.

[0011] (6): In the above scheme (4) or (5), when the internal combustion engine is in operation and is in stoichiometric operation and the battery is charged to a level below the reference value, the control device increases the speed of the internal combustion engine to the speed set in the rich operation, switches the stoichiometric operation to the rich operation, increases the output of the electric motor, and limits the rate of increase of the output.

[0012] (7): In any of the above (1) to (6), when the internal combustion engine is in operation and is in the stoichiometric ratio operation state where the internal combustion engine and the drive wheel are not mechanically connected, the control device increases the speed of the internal combustion engine to the speed set in the rich operation, and when the temperature of the catalyst in the internal combustion engine becomes above a specified value, the stoichiometric ratio operation is switched to the rich operation.

[0013] (8): Another aspect of the present invention provides a vehicle comprising an internal combustion engine, a generator rotatable under the action of the internal combustion engine, a battery for storing the electricity generated by the rotation of the generator, an electric motor supplied with electricity from the battery and outputting driving force to the drive wheels, and a control device, wherein the control device begins to increase the speed of the internal combustion engine to a speed set for rich operation in which the ratio of fuel to oxygen in the internal combustion engine is higher than the stoichiometric air-fuel ratio when the output required for the internal combustion engine to operate in a stoichiometric air-fuel ratio state where the internal combustion engine is not mechanically connected to the drive wheels is above a threshold.

[0014] According to the schemes (1) to (8), the operating line of the internal combustion engine can be switched regardless of the operating point of the internal combustion engine, and the discomfort felt by the passengers can be reduced.

[0015] According to schemes (2) and (3), when switching to rich operation to increase the torque of the internal combustion engine, the discomfort felt by the occupants can be reduced.

[0016] According to the schemes (4) to (6), when switching to rich operation to increase the output of the internal combustion engine, the discomfort felt by the occupants can be reduced.

[0017] According to the scheme in (7), the operating mode can be switched appropriately based on the temperature of the catalyst. Attached Figure Description

[0018] Figure 1 This is a diagram illustrating an example of the structure of vehicle M in this embodiment.

[0019] Figure 2 This is a diagram illustrating an example of the functional structure of a control device.

[0020] Figure 3 It is a diagram used to illustrate the summary of the actions performed by the control device.

[0021] Figure 4 This is a diagram illustrating an example of the engine's optimal fuel economy operating line.

[0022] Figure 5 This is a flowchart illustrating an example of the process of actions performed by a control device.

[0023] Figure 6 This is a timing diagram illustrating an example of the flow of actions performed by a control device. Detailed Implementation

[0024] Hereinafter, embodiments of the control device and vehicle of the present invention will be described with reference to the accompanying drawings.

[0025] [Overall Structure]

[0026] Figure 1 This diagram illustrates an example of the structure of the vehicle M according to this embodiment. The vehicle M shown is a hybrid vehicle capable of switching between series and parallel operation. In series operation, the engine and drive wheels are not mechanically connected; the engine's power is dedicated to generating electricity via a generator, which is then supplied to an electric motor for driving. In parallel operation, the engine and drive wheels are mechanically (or fluidly connected via a torque converter, etc.), and the engine's power can be transmitted to the drive wheels or used for generating electricity. Figure 1 The vehicle M with the structure shown can switch between series and parallel modes by engaging or disengaging the lock-up clutch 14.

[0027] like Figure 1As shown, vehicle M is equipped with, for example, an engine 10, a first motor (generator) 12, a lock-up clutch 14, a gearbox 16, a second motor (electric motor) 18, a braking device 20, drive wheels 25, a PCU (Power Control Unit) 30, a battery 60, battery sensors 62 (including voltage, current, and temperature sensors), a throttle opening sensor 70, a vehicle speed sensor 72, and a brake pedal pressure sensor 74, among other vehicle sensors. This vehicle M, as a drive source, at least includes an engine 10, a second motor 18, and a battery 60.

[0028] Engine 10 is an internal combustion engine that outputs power by burning fuels such as gasoline. Engine 10 is, for example, a reciprocating engine equipped with a combustion chamber, cylinder and piston, intake valve, exhaust valve, fuel injection device, spark plug, connecting rod, crankshaft, etc. Alternatively, engine 10 can also be a rotary engine.

[0029] The first motor 12 is, for example, a three-phase alternator. The first motor 12 is connected to the rotor of the engine 10 via the output shaft (e.g., crankshaft) and uses the power output by the engine 10 to generate electricity. The output shaft of the engine 10 and the rotor of the first motor 12 are connected to the drive wheel 25 via a lock-up clutch 14.

[0030] The lock-up clutch 14 switches the state of the output shaft of the engine 10 and the rotor of the first motor 12 connected to the drive wheel 25 side and disconnected from the drive wheel 25 side, according to the instructions from the PCU 30.

[0031] Gearbox 16 is a transmission. Gearbox 16 changes the power output from engine 10 and transmits it to the drive wheels 25. The gear ratio of gearbox 16 is specified by PCU 30.

[0032] The second motor 18 is, for example, a three-phase AC motor. The rotor of the second motor 18 is connected to the drive wheel 25. The second motor 18 uses the supplied electricity and outputs power to the drive wheel 25. In addition, the second motor 18 uses the kinetic energy of the vehicle M to generate electricity when the vehicle M decelerates, and stores the generated electricity in the battery 60 via the second converter 34 and VCU40 described later.

[0033] The braking device 20 includes, for example, a brake caliper, a hydraulic cylinder that transmits hydraulic pressure to the brake caliper, and an electric motor that generates hydraulic pressure in the hydraulic cylinder. The braking device 20 may also include a backup mechanism for transmitting hydraulic pressure generated by operating the brake pedal via a master hydraulic cylinder to another hydraulic cylinder. The braking device 20 is not limited to the structure described above; it may also be an electronically controlled hydraulic braking device that transmits hydraulic pressure from the master hydraulic cylinder to another hydraulic cylinder.

[0034] PCU30 includes, for example, a first converter 32, a second converter 34, a VCU (Voltage Control Unit) 40, and a control device 50. The structure that integrates these components into a single PCU30 is just one example; these components can also be distributed.

[0035] The first converter 32 and the second converter 34 are, for example, AC-DC converters. The DC-side terminals of the first converter 32 and the second converter 34 are connected to a DC line DL. A battery 60 is connected to the DC line DL via a VCU 40. The first converter 32 converts the AC power generated by the first motor 12 into DC power and outputs it to the DC line DL, or converts the DC power supplied via the DC line DL into AC power and supplies it to the first motor 12. Similarly, the second converter 34 converts the AC power generated by the second motor 18 into DC power and outputs it to the DC line DL, or converts the DC power supplied via the DC line DL into AC power and supplies it to the second motor 18.

[0036] VCU40 is, for example, a DC-DC converter. VCU40 boosts the power supplied from battery 60 and outputs it to DC line DL.

[0037] The function of the control device 50 is described later. The battery 60 is, for example, a secondary battery such as a lithium-ion battery.

[0038] A throttle opening sensor 70 is installed on the accelerator pedal, which serves as an operating element for receiving acceleration instructions from the driver. It detects the amount of throttle pedal operation and outputs this as the throttle opening to the control device 50. A vehicle speed sensor 72 includes, for example, wheel speed sensors mounted on each wheel and a speed computer. It combines the wheel speeds detected by the wheel speed sensors to derive the vehicle speed (vehicle speed) and outputs it to the control device 50. A brake pedal pressure sensor 74 is installed on the brake pedal, which serves as an operating element for receiving deceleration or stop instructions from the driver. It detects the amount of brake pedal operation and outputs this as the brake pedal pressure to the control device 50.

[0039] Figure 2This diagram illustrates an example of the functional structure of the control device 50. The control device 50 includes, for example, an engine control unit 51, a motor control unit 52, a brake control unit 53, a battery / VCU control unit 54, and a hybrid power control unit 55. These components are implemented, for example, by executing programs (software) using a hardware processor such as a CPU (Central Processing Unit). Alternatively, some or all of these components can be implemented using hardware (including the circuitry) such as LSI (Large Scale Integration), ASIC (Application Specific Integrated Circuit), FPGA (Field-Programmable Gate Array), and GPU (Graphics Processing Unit), or through a combination of software and hardware.

[0040] In addition, the engine control unit 51, motor control unit 52, brake control unit 53 and battery / VCU control unit 54 can each be replaced with a control device separate from the hybrid power control unit 55, such as an engine ECU (Electronic Control Unit), motor ECU, brake ECU and battery ECU.

[0041] The engine control unit 51 performs ignition control, throttle opening control, fuel injection control, and fuel cut-off control of the engine 10 according to instructions from the hybrid power control unit 55. For example, the engine control unit 51 receives command values ​​related to the speed and torque of the engine 10 from the hybrid power control unit 55 and performs control so that the engine 10 operates according to the command values.

[0042] The motor control unit 52 controls the switching of the first converter 32 and / or the second converter 34 according to the instructions from the hybrid power control unit 55.

[0043] The braking control unit 53 controls the braking device 20 according to the instructions from the hybrid power control unit 55.

[0044] The battery VCU control unit 54 calculates the SOC (State of Charge) of the battery 60 based on the output of the battery sensor 62 installed on the battery 60, and outputs it to the hybrid power control unit 55. In addition, the battery VCU control unit 54 activates the VCU 40 according to the instruction from the hybrid power control unit 55, thereby increasing the voltage of the DC line DL.

[0045] The hybrid power control unit 55 determines the driving mode based on the outputs of the throttle opening sensor 70, vehicle speed sensor 72, and brake pedal pressure sensor 74, and outputs instructions to the engine control unit 51, motor control unit 52, brake control unit 53, and battery / VCU control unit 54 according to the driving mode. The hybrid power control unit 55 further determines command values ​​related to the engine speed and torque of the engine 10 in each driving mode, and sends the determined command values ​​to the engine control unit 51.

[0046] [Various driving modes]

[0047] The following describes the driving modes determined by the hybrid power control unit 55. The following driving modes exist.

[0048] (1) Series hybrid driving mode (ECVT)

[0049] In the series hybrid driving mode, the hybrid control unit 55 disengages the lock-up clutch 14, supplies fuel to the engine 10 to operate the engine 10, and provides electricity generated by the first motor 12 to the battery 60 and the second motor 18. Furthermore, the second motor 18 is driven using the electricity supplied from the first motor 12 or the battery 60, and the vehicle M is propelled by the power from the second motor 18. The series hybrid driving mode is an example of a mode in which the internal combustion engine operates without mechanical connection to the drive wheels.

[0050] (2) EV Driving Mode (EV)

[0051] In EV driving mode, the hybrid control unit 55 disengages the lock-up clutch 14 and uses the power supplied from the battery 60 to drive the second motor 18, thereby driving the vehicle M with the power from the second motor 18.

[0052] (3) Engine-driven driving mode (LU)

[0053] In engine-driven driving mode, the hybrid power control unit 55 engages the lock-up clutch 14, causing the engine 10 to consume fuel and operate, and transmitting at least a portion of the power output from the engine 10 to the drive wheels 25 to propel the vehicle M. At this time, the first motor 12 may or may not generate electricity.

[0054] (4)Regeneration

[0055] During regeneration, the hybrid power control unit 55 disengages the lock-up clutch 14, allowing the second motor 18 to generate electricity using the kinetic energy of the vehicle M. The electricity generated during regeneration is stored in the battery 60 or discarded through a waste-electricity operation.

[0056] [Summary of the actions performed by the control device 50]

[0057] Next, refer to Figure 3 Here is a summary of the actions performed by the control device 50. Unless otherwise specified, the actions of the control device 50 described below are assumed to be performed when the vehicle M is traveling in ECVT mode. In this case, the engine 10 is not directly connected to the drive wheels 25, so the control device 50 is not limited by the vehicle speed and can select an unlimited number of combinations of speed and torque required to achieve the specified output of the engine 10 (output = speed × torque).

[0058] Figure 3 It is a diagram used to illustrate the summary of the actions performed by the control device 50. Figure 3 In the upper part, SOL represents the maximum output line of stoichiometry, which indicates the relationship between the engine speed during operation and the maximum output at that time. ROL represents the maximum output line of richness, which indicates the relationship between the engine speed during operation and the maximum output at that time. Figure 3 In the lower part, STL represents the stoichiometric maximum torque line, which indicates the relationship between the engine speed and the maximum torque during stoichiometric operation of the engine 10. RTL represents the rich maximum torque line, which indicates the relationship between the engine speed and the maximum torque during rich operation of the engine 10. Here, stoichiometric operation means that the engine 10 operates according to the stoichiometric air-fuel ratio, while rich operation means that the engine 10 operates when the fuel-to-oxygen ratio is higher than the stoichiometric air-fuel ratio. Figure 3 In the diagram, the speed and torque at point T1 correspond to the output at point O1, the speed and torque at point T2 correspond to the output at point O2, and the speed and torque at point T3 correspond to the output at point O3. Hereinafter, the speed SMR at point T1 is sometimes referred to as the "maximum stoichiometric speed," the torque SMT at point T1 as the "maximum stoichiometric torque," the speed RMR at point T3 as the "maximum speed for rich fuel," and the torque RMT at point T3 as the "maximum torque for rich fuel."

[0059] Now, for example, suppose that during stoichiometric operation of vehicle M, the driver forcefully depresses the accelerator pedal, and the throttle opening sensor 70 detects a high throttle opening. As a result, engine 10 operates at point O1, where its output is at its maximum on the stoichiometric maximum output line SOL. When this high-output operation continues for a certain period, the temperature of the catalyst in engine 10 rises, potentially damaging the functionality of engine 10. In such cases, conventional technology, when the temperature of the catalyst in engine 10 is detected to exceed a predetermined value, switches the operating mode of engine 10 from stoichiometric operation to rich operation, using the heat of vaporization of auxiliary fuel to cool engine 10. That is, conventional technology switches the operating point of engine 10 from point O1, where its output is at its maximum on the stoichiometric maximum output line SOL, to point O3, where its output is at its maximum on the rich maximum output line ROL.

[0060] However, when switching the operation of engine 10 from stoichiometric operation to rich stoichiometric operation, such as Figure 3 As shown by the dotted arrow, the engine speed and torque of engine 10 suddenly increase, which may cause a sense of unease among the occupants of vehicle M.

[0061] Therefore, in this embodiment, when the driver forcefully depresses the accelerator pedal during operation of the vehicle M at its stoichiometric ratio, and the throttle opening sensor 70 detects a demand output exceeding a threshold, the control device 50, even if the temperature of the catalyst in the engine 10 is less than a specified value, will start changing the engine speed of the engine 10 to the speed at which the output on the maximum enrichment output line ROL reaches its maximum at point O3, even when the demand output is detected. That is, the control device 50 gradually changes the operating point of the engine 10 from point O1 to point O2.

[0062] Subsequently, when the control device 50 detects that the temperature of the catalyst in the engine 10 has reached a predetermined value, it switches the operating mode of the engine 10 from stoichiometric operation to rich operation, increasing the torque of the engine 10 and thus switching the operating point of the engine 10 from point O2 to point O3. At this time, when increasing the torque of the engine 10, the control device 50 performs rate limiting processing to restrict the amount of torque increase per unit time (i.e., the rate of increase), thereby preventing the occupants of the vehicle M from feeling a sudden increase in torque. In particular, when the speed of the vehicle M is low, i.e., when the second motor 18 is in the low-speed rotation region, it is possible to generate high torque. Therefore, the lower the speed of the vehicle M, the stronger the restriction on the rate of torque increase by the control device 50.

[0063] When engine 10 switches from stoichiometric operation to rich operation, the control device 50 increases the output of the second motor 18 along with the increased output. For example, if the output provided by the second motor 18 is insufficient relative to the required output during stoichiometric operation, the control device 50 increases the output of the second motor 18. However, similar to the torque situation, a sudden increase in the output of the second motor 18 can cause discomfort to the occupants of vehicle M. Therefore, when increasing the output of the second motor 18, the control device 50 performs rate limiting processing to restrict the increase in output per unit time (i.e., the rate of increase), and the lower the speed of vehicle M, the stronger the restriction on the rate of increase in output. With the structure described above, the control device 50 can smoothly switch from stoichiometric operation to rich operation without causing discomfort to the occupants of vehicle M.

[0064] The above explanation is based on the following condition: when the vehicle M is operating at its stoichiometric ratio or rich concentration, the driver forcefully depresses the accelerator pedal, and the throttle opening sensor 70 detects a demand output exceeding the threshold. That is, under such conditions, the control device 50 sets the engine speed and torque of the engine 10 to a point on the stoichiometric ratio maximum torque line STL or the rich concentration maximum torque line RTL.

[0065] On the other hand, if the driver does not forcefully press the accelerator pedal and the throttle opening sensor 70 does not detect the required output above the threshold, the control device 50 sets the engine speed and torque of the engine 10 to a point on the optimal fuel economy operating line that satisfies the required output. Figure 4 This is a diagram illustrating an example of the optimal fuel economy operating line for engine 10. The optimal fuel economy operating line represents the combination of engine speed and torque that achieves the best fuel economy.

[0066] exist Figure 4 In this diagram, FOL represents the optimal fuel economy operating line, and NOL represents the equal output line that achieves the required output. When the throttle opening sensor 70 detects a required output exceeding a threshold, the control device 50 sets the engine speed and torque of the engine 10 to a point on the maximum stoichiometric torque line STL or the rich maximum torque line RTL that achieves maximum output. Conversely, when the throttle opening sensor 70 detects a required output below the threshold, the control device 50 sets the engine speed and torque of the engine 10 to the intersection point P between the equal output line EOL and the optimal fuel economy operating line FOL. That is, when the driver of vehicle M requests high output, the engine speed and torque are set to the operating point O1 or O3 that achieves maximum output; conversely, when the driver of vehicle M does not request high output, the engine speed and torque are set to the operating point P that achieves optimal fuel economy for the given required output.

[0067] [Flow of actions performed by control device 50]

[0068] Next, refer to Figure 5 This will explain the process of the actions performed by the control device 50. Figure 5 This is a flowchart illustrating an example of the process of actions performed by the control device 50.

[0069] First, the control device 50 determines whether the temperature of the catalyst in the engine 10 is above a predetermined value (step S101). If the temperature of the catalyst in the engine 10 is not determined to be above the predetermined value, the control device 50 determines whether the required output is above a threshold value (step S102). If the required output is not determined to be above the threshold value, the control device 50 performs stoichiometric operation and sets the upper limit of the engine speed of the engine 10 to the maximum stoichiometric speed SMR (step S103). Furthermore, the control device 50 sets the upper limit of the engine torque of the engine 10 to the maximum stoichiometric torque SMT (step S104). Next, the control device 50 operates the engine speed and torque at the intersection point P between the optimal fuel economy operating line and the required output within the set upper limit of the engine speed and the upper limit of the torque (step S105). Next, the control device 50 sets the rich fuel preparation flag to off (step S106) and returns to step S101 for processing. The rich fuel readiness indicator, as mentioned above, is an identification message indicating whether the process of increasing the stoichiometric ratio of the operating speed to the rich fuel maximum speed (RMR) has begun in preparation for a smooth transition to rich fuel operation in the future.

[0070] If the required output is determined to be above a threshold, the control device 50 performs stoichiometric operation and sets the upper limit of engine speed 10 to the maximum speed RMR for rich fuel (step S107). Furthermore, the control device 50 sets the upper limit of engine torque 10 to the maximum torque SMT for stoichiometric ratio (step S108). Next, the control device 50 begins to increase the speed to the set upper limit, and simultaneously operates the engine 10 of vehicle M at the upper limit of torque (step S109). Then, the control device 50 sets the rich fuel preparation flag to "on" (step S110) and returns to step S101 for further processing.

[0071] If the temperature of the catalyst in engine 10 is determined to be above a specified value, the control device 50 determines whether the rich fuel preparation flag is turned on (step S111). If the rich fuel preparation flag is not turned on, this means that no output above the required threshold has been requested in any of the determination cycles, and the catalyst temperature has reached above the specified value. Therefore, the control device 50 performs normal rich operation and sets the upper limit of the engine speed to the rich fuel maximum speed RMR (step S112). Furthermore, the control device 50 sets the upper limit of the engine torque to the rich fuel maximum torque RMT (step S113). Next, within the set upper limit of the engine speed and the upper limit of the torque, the control device 50 operates the engine 10 of vehicle M at the intersection point P between the optimal fuel economy operating line and the required output (step S114), and returns to step S101 for processing.

[0072] If the rich fuel preparation indicator is determined to be on, the control device 50 sets the upper limit of engine speed to the maximum rich fuel speed RMR (step S115). Next, the control device 50 uses the vehicle speed sensor 72 and refers to the speed of the vehicle M to set the torque upper limit change amount corresponding to the speed of the vehicle M (step S116). Then, the control device 50 obtains the current torque upper limit value by adding the torque upper limit change amount to the previous torque upper limit value (step S117). In this step, the rich fuel preparation indicator is set to on, thus ensuring the existence of the previous torque upper limit value. Furthermore, the control device 50 operates the engine 10 of the vehicle M at the set upper limit of engine speed and torque (step S118) and returns to step S101 for further processing. As long as the catalyst temperature is above the specified value, the processes S115 to S118 are repeated, thus the torque upper limit value is close to the maximum rich fuel torque RMR, and the engine 10 is cooled through rich fuel operation. The processing in step S117 can also end when the upper limit of torque is sufficiently close to or consistent with the maximum torque RMT of rich fuel.

[0073] According to the flowchart described above, when the required output in the stoichiometric operation of engine 10 reaches a threshold value, the engine speed is initially increased only to the maximum speed RMR for rich fuel. Then, when the catalyst temperature reaches a specified value, the torque of engine 10 is increased while simultaneously bringing the maximum torque value close to the maximum torque RMT for rich fuel. This allows the occupants of vehicle M to switch seamlessly from stoichiometric operation to rich fuel operation.

[0074] Next, refer to Figure 6 This will illustrate the flow of actions performed by the control device 50 in the illustrated scenario. Figure 6 This is a timing diagram illustrating an example of the flow of actions performed by the control device 50. Figure 6 In the diagram, solid lines represent the operation of the control device 50 based on this embodiment, and dashed lines represent the operation of the control device based on conventional technology (the operation outside the dashed line section is the same as the operation of this embodiment).

[0075] First, before time point t1, the output is required to be below a threshold and the catalyst temperature is below a specified value, so engine 10 operates at stoichiometric ratio. Next, at time point t1, the output is required to be above the threshold. Therefore, control device 50 changes the upper speed limit from maximum stoichiometric ratio speed (SMR) to maximum rich fuel speed (RMR), and begins to increase the speed to the maximum rich fuel speed (RMR). As a result, the engine speed of 10 reaches the maximum rich fuel speed (RMR) at time point t3. Then, at time point t4, when the catalyst temperature reaches a specified value, control device 50 switches engine 10 from stoichiometric ratio operation to rich operation, gradually increasing the upper torque limit from maximum stoichiometric ratio torque (SMT) to maximum rich fuel torque (RMT) through rate limiting processing. As a result, at time point t5, the engine speed and torque of 10 reach the maximum rich fuel speed (RMR) and maximum rich fuel torque (RMT) respectively, allowing the occupants of vehicle M to switch from stoichiometric ratio operation to rich operation without any noticeable difference.

[0076] On the other hand, in the case of a control device based on conventional technology, at time point t4, the speed is changed from the maximum speed of stoichiometric ratio (SMR) to the maximum speed of rich fuel (RMR), and the torque is changed from the maximum torque of stoichiometric ratio (SMT) to the maximum torque of rich fuel (RMT). Therefore, the occupants of vehicle M sometimes feel uncomfortable with the sudden increase in torque.

[0077] Furthermore, the output of the second motor 18 also increases as the control device 50 increases due to the increased output resulting from switching from stoichiometric operation to concentrated operation. Figure 6 In this scenario, although the required output is above the threshold at time t1, the output of the second motor 18 remains constant after time t2. The reason for this is conceivable: the SoC of the battery 60 is below the baseline value, so even if the required output is above the threshold, the output of the second motor 18 does not increase. Therefore, when the SoC of the battery 60 is below the baseline value, the control device 50 increases the output of the second motor 18 after switching from stoichiometric operation to concentrated operation. At this time, similar to the torque case, the upper limit of the output is gradually increased through rate limiting processing to prevent the occupants of vehicle M from experiencing any abrupt change in output.

[0078] According to the embodiments of the present invention described above, regardless of the operating point of the engine 10, the operating mode of the engine 10 is smoothly switched from stoichiometric operation to rich operation based on the temperature of the catalyst and the required output. Therefore, the operating line of the internal combustion engine can be switched regardless of its operating point, while reducing discomfort experienced by the occupants.

[0079] The above description illustrates specific embodiments of the present invention, but the present invention is not limited to such embodiments in any way, and various modifications and substitutions can be made without departing from the spirit of the present invention.

Claims

1. A control device that is a control device of a vehicle, the vehicle is provided with an internal combustion engine, a generator that is able to rotate under the action of the internal combustion engine, a storage battery that stores electric power that is emitted by rotation of the generator, and an electric motor that is supplied with electric power from the storage battery and outputs driving force to a drive wheel, wherein at a timing at which an output required when the internal combustion engine is operating in a stoichiometric ratio operation in which the internal combustion engine is operating at a theoretical air-fuel ratio and the chemical equivalent ratio operation is being performed becomes a threshold value or more in a state in which the internal combustion engine is operating and the drive wheel is not mechanically linked, increasing the rotational speed of the internal combustion engine to a rotational speed set in a rich operation in which the ratio of fuel to oxygen of the internal combustion engine is higher than the theoretical air-fuel ratio is started, after the rotational speed of the internal combustion engine is increased to the rotational speed set in the rich operation while the chemical equivalent ratio operation is being performed, the chemical equivalent ratio operation is switched to the rich operation to increase the torque of the internal combustion engine.

2. The control device according to claim 1, wherein in a case in which, after the rotational speed of the internal combustion engine is increased to the rotational speed set in the rich operation while the chemical equivalent ratio operation is being performed, the chemical equivalent ratio operation is switched to the rich operation to increase the torque of the internal combustion engine in a state in which the internal combustion engine is operating and the drive wheel is not mechanically linked while the chemical equivalent ratio operation is being performed, the rate of increase of the torque is limited.

3. The control device according to claim 2, wherein the lower the speed of the vehicle, the more the degree of limitation of the rate of increase of the torque is strengthened.

4. A control device that is a control device of a vehicle, the vehicle is provided with an internal combustion engine, a generator that is able to rotate under the action of the internal combustion engine, a storage battery that stores electric power that is emitted by rotation of the generator, and an electric motor that is supplied with electric power from the storage battery and outputs driving force to a drive wheel, wherein at a timing at which an output required when the internal combustion engine is operating in a stoichiometric ratio operation in which the internal combustion engine is operating at a theoretical air-fuel ratio and the chemical equivalent ratio operation is being performed becomes a threshold value or more in a state in which the internal combustion engine is operating and the drive wheel is not mechanically linked, increasing the rotational speed of the internal combustion engine to a rotational speed set in a rich operation in which the ratio of fuel to oxygen of the internal combustion engine is higher than the theoretical air-fuel ratio is started, after the rotational speed of the internal combustion engine is increased to the rotational speed set in the rich operation while the chemical equivalent ratio operation is being performed, the chemical equivalent ratio operation is switched to the rich operation to increase the output of the electric motor.

5. The control device according to any one of claims 1 to 4, wherein in a case in which, after the rotational speed of the internal combustion engine is increased to the rotational speed set in the rich operation while the chemical equivalent ratio operation is being performed, the chemical equivalent ratio operation is switched to the rich operation to increase the output of the electric motor in a state in which the internal combustion engine is operating and the drive wheel is not mechanically linked while the chemical equivalent ratio operation is being performed, the rate of increase of the output is limited.

6. The control device according to claim 5, wherein the lower the speed of the vehicle, the more the degree of limitation of the rate of increase of the output is strengthened.

7. The control device according to claim 5, wherein In a case where the internal combustion engine is operated in the stoichiometric ratio operation and the state of charge of the battery is below a reference value in a state where the internal combustion engine is not mechanically linked to the drive wheels, the engine speed of the internal combustion engine is increased to a speed set in the rich operation, and the stoichiometric ratio operation is switched to the rich operation to increase the output of the motor, and the rate of increase of the output is limited.

8. The control device according to claim 6, wherein In a case where the internal combustion engine is operated in the stoichiometric ratio operation and the state of charge of the battery is below a reference value in a state where the internal combustion engine is not mechanically linked to the drive wheels, the engine speed of the internal combustion engine is increased to a speed set in the rich operation, and the stoichiometric ratio operation is switched to the rich operation to increase the output of the motor, and the rate of increase of the output is limited.

9. The control device according to any one of claims 1 to 4, wherein In a case where the internal combustion engine is operated in the stoichiometric ratio operation and the temperature of the catalyst in the internal combustion engine becomes a prescribed value or more when the engine speed of the internal combustion engine is increased to a speed set in the rich operation in a state where the internal combustion engine is not mechanically linked to the drive wheels, the stoichiometric ratio operation is switched to the rich operation.

10. The control device according to claim 5, wherein In a case where the internal combustion engine is operated in the stoichiometric ratio operation and the temperature of the catalyst in the internal combustion engine becomes a prescribed value or more when the engine speed of the internal combustion engine is increased to a speed set in the rich operation in a state where the internal combustion engine is not mechanically linked to the drive wheels, the stoichiometric ratio operation is switched to the rich operation.

11. The control device according to claim 6 or 7, wherein In a case where the internal combustion engine is operated in the stoichiometric ratio operation and the temperature of the catalyst in the internal combustion engine becomes a prescribed value or more when the engine speed of the internal combustion engine is increased to a speed set in the rich operation in a state where the internal combustion engine is not mechanically linked to the drive wheels, the stoichiometric ratio operation is switched to the rich operation.

12. A vehicle that is provided with an internal combustion engine, a generator that is rotatable by the action of the internal combustion engine, a battery that stores electric power generated by the rotation of the generator, a motor that is supplied with electric power from the battery and outputs driving force to drive wheels, and a control device, wherein The control device starts increasing the engine speed of the internal combustion engine to a speed set in a rich operation in which the ratio of fuel to oxygen of the internal combustion engine is higher than a theoretical air-fuel ratio when the required output of the internal combustion engine operating in the stoichiometric ratio operation in which the internal combustion engine operates at the theoretical air-fuel ratio becomes a threshold value or more in a state where the internal combustion engine is not mechanically linked to the drive wheels, After increasing the rotational speed of the internal combustion engine to the rotational speed set in the rich operation, the stoichiometric-equivalent ratio operation is switched to the rich operation to increase the torque of the internal combustion engine.

13. A vehicle comprising: an internal combustion engine; a generator that is rotatable by the internal combustion engine; a storage battery that stores electric power generated by rotation of the generator; an electric motor that is supplied with electric power from the storage battery and outputs drive power to drive wheels; and a control device, wherein the control device starts increasing the rotational speed of the internal combustion engine to a rotational speed set in a rich operation in which the ratio of fuel to oxygen of the internal combustion engine is higher than a theoretical air-fuel ratio when an output required when the internal combustion engine is operating in a state in which the internal combustion engine is not mechanically linked to the drive wheels and the stoichiometric-equivalent ratio operation in which the internal combustion engine is operating at the theoretical air-fuel ratio is being performed becomes a threshold value or more, after increasing the rotational speed of the internal combustion engine to the rotational speed set in the rich operation, the stoichiometric-equivalent ratio operation is switched to the rich operation to increase the output of the electric motor.

Images